Recovery and Recolonisation Processes in the Area Disturbed by a Polymetallic Nodule Collector Simulator

摘要

In July 199S, Interoceanmetal Joint Organization (IOM) carried out a field experiment called the Benthic Impact Experiment '95 (IOM BIE'95) within the IOM pioneer area in the Pacific's Clarion Clipperton Fracture Zone. The experiment was aimed at studying effects of disturbance, produced by simulated nodule mining, on benthic communities and their habitat. The disturbance was effected by a Deep Sea Sediment Resuspension System (the so-called Disturber towed on the bottom along a course laid out within a 2 x 1.5 km test site. Before and immediately after the Disturber operation, the area was surveyed with the aid of a continuous deep sea camera/video recorder to document changes in the sediment, megabenthos and its Lebensspuren occurring within the test site. In April-May 1997, 22 months after the original disturbance, the test site was revisited and photo/video-surveyed again. The observed changes in the sedimentary cover involved a considerable weathering of Disturber tracks, most likely due to strong near-bottom currents and/or benthic storms. The intensive feeding activity of motile megafauna, documented immediately after the disturbance, continued 22 months later as evidenced by frequent appearances of fish, shrimps, and holothurians in the test area and lattices of relatively fresh biogenic traces visible on photographs and video recordings.